1. Field of the Invention
The present invention relates to fish processing and more particularly to an improved method and apparatus for processing a frozen fish body into a plurality of transverse fish body sections and wherein a wheeled carriage carrying the fish body travels upon a railway that traverses a plurality of work stations, each equipped with a cutting blade that cuts a transverse fish body section from the fish body.
2. General Background
In the processing of fish such as tuna, it is common to freeze a catch of fish at sea, and to process the catch on shore. The processing normally involves thawing the fish followed by manual operations of slitting the fish belly and removing the viscera. The visceral cavity is then washed with water, and the tuna inspected for spoilage. The tuna is then usually cooked whole in a batch type operation.
Manual prior art methods of processing tuna are described in greater detail in U.S. Pat. No. 3,594,191 issued to J. M. Lapeyre, an applicant herein. The '191 Lapeyre patent discloses the concept of cutting the tuna in sections at spaced intervals and thereafter separating the edible loin portions to provide discrete cannable portions. A later U.S. Pat. No. 3,593,370 entitled "Method of Butchering Tuna" issued to J. M. Lapeyre, describes a method for processing such transverse tuna sections while frozen. The method of butchering frozen tuna described in the '370 Lapeyre patent includes the subdivision of the whole fish into a plurality of transverse cross-sections and subsequently subdividing the cross-sections into frozen segments. The junctures between the segments are along lines generally parallel to the longitudinal axis of the fish and to the backbone thereof. Each transverse fish section is skinned and the skinned sections operated on to effect a separation of the scrap parts of the sections from the loin meat parts, while the latter were still in at least a partially frozen condition.
U.S. Pat. No. 3,800,363 issued to J. M. Lapeyre entitled "Tuna Butchering Method and System", and U.S. Pat. No. 4,738,004 also issued to J. M. Lapeyre, entitled "Tuna Butchering Method" describe butchering methods and systems for separating the edible loin portions of transverse tuna slices provided by subdivision of a frozen whole tuna. U.S. Pat. Nos. 3,594,191; 3,593,370; 3,800,363; and 4,738,004 are incorporated herein by reference.
One of the problems not addressed in any of the above-referenced Lapeyre patents is the problem of high speed, high volume processing of fish bodies (usually frozen) while maintaining precise transverse cuts and precise dimensions between cuts to give usable transverse sections of consistent thickness even when the fish bodies vary greatly in size and shape. In the processing of a high volume of tuna, for example, the fish bodies are normally received in a frozen state, are often misshapen and of varying sizes. In any attempt to process a high volume of frozen fish into transverse fish body sections, the differential sizes present a problem. A processing "machine" will typically not "know" the size of the fish being processed at any given time if an inexpensive "machine" is being used to cut the fish in an automated, high speed fashion. For example, one fish might weigh ten (10) pounds and be twenty-four (24) inches long while the next fish being processed might be thirty (30) pounds and thirty-five (35) inches long. This problem is aggravated when a very high delivery rate removes any chance for an interim adjustment between fish.
Another problem when attempting to cut the fish into transverse fish body sections is that the fish being processed are usually frozen and are difficult to grip and support in the same position at all times. Any slight shift of the fish position can reduce precision in the cutting operation.
Another problem of processing a large volume of fish of differing sizes which are frozen is the problem of gripping each fish in such a way as not to damage the fish yet hold it securely. In any manufacturing or processing plant, a fish would be difficult to hold if frozen. An additional problem is the variation in temperature which exists between the fish body and the equipment being used to support it. The flow of heat between equipment and fish could cause the fish to thaw prematurely or at least to partially thaw, making a holding of the fish not only difficult but unpredictable, possibly creating damage to the fish.